1 Adult identification
The double-spotted leaf beetle, also known as the long-tarsal leaf beetle, belongs to the Coleoptera leaf beetle family, and is a new type of pest that harms corn. The adult body is 3.6 to 4.8 mm long and 2.8 mm wide, with 11 filamentous antennae, the end is black, and the length is 2/3 of the body length; the compound eyes are large and oval; the dorsal plate of the anterior thorax is wider than long, the surface is raised, and there are many small notches; the small shield is black, triangular; the elytra cloth is lined with fine dots, and each coleope half has l nearly circular pale spots, surrounded by black, and the lateral side of the pale spots is not completely closed, and the back of the two wings is rounded. The simple identification method is that the adult has a large pale yellow spot at the base of each of the two elytra wings, which is black on all sides, and the half of the elytra end is yellow.
2 Habits of life
Double-spotted fluorescent leaf beetle has a certain degree of flight, adult insects are more sensitive to the intensity of light and temperature, strong light and high temperature at noon, then the ability to fly is strong, the amount of eating leaves is large; from morning to night, the light is weak and the temperature is low, the flight force is poor, the activity is small, and often hides in the back of the leaf to roost.
3 Harmful symptoms
Maize double-spotted fluorescent leaf beetle mainly occurs in July to September, with adult insects as the pest of corn leaves, the light leaves are yarn-like, and the heavy corn leaves are dried up. The insect has a group habit and tender habit of harm, often concentrated in 1 plant from top to bottom to eat corn leaf flesh, young leaves are bitten into holes, the middle and lower leaves are damaged, residual reticular veins or epidermis, from a distance to appear as a small area of irregular white spots, the impact on photosynthesis is greater; after the corn is extracted, the insect likes to eat anthers and filaments, affecting the normal flowering and pollening of corn, and is easy to form rotten grains.
4 Occurrence
Maize double-spotted firefly beetles occur in one generation per year, overwintering under the topsoil as scattered eggs, hatching in early to mid-May of the following year, and the larvae have been living in the soil, preferring to eat the roots of grass crops or weeds; the first feathered adults live on the weeds on the edge of the ground and then move into the corn field; and enter the adult bloom period in mid-to-late July, and continue to be harmful until September.
The degree of occurrence of bilocarpus fireflies depends on a combination of factors such as the source base, climatic conditions and surrounding environmental factors. Under the climatic conditions of normal years, the more eggs survive in winter, the more larvae hatch in the next year, and the greater the harm.
4.1 Climatic impacts
Mainly determined by the temperature and humidity in July and August, high temperature and drying are extremely beneficial to the occurrence of double-spotted fluorescent leaf beetles, and heavy precipitation occurs heavily when precipitation is small, and light rainfall occurs more, and heavy rain is extremely unfavorable to it.
4.2 Environmental Factors
The single layout of crop varieties, the implementation of large-scale continuous cropping, and the general adoption of measures such as dense planting and high fertilizer water management are conducive to the accumulation of maize diseases and insect sources. Extensive management and overgrown weeds along the roadside and in the field provide a good ecological environment for the spawning and reproduction of insect pests. In addition, the degree of occurrence is also related to the soil, which occurs early and is harmful in clay soil, and occurs significantly less in sandy soil and sandy land. In addition, due to relatively poor production conditions in hilly mountains, drought and weeds, the occurrence of double-spotted fluorescent leaf beetles in corn fields is also relatively heavy.
5 Integrated control
According to the occurrence law and living habits of the maize field double-spotted fluorescent leaf beetle, comprehensive measures such as agricultural control, biological control and chemical control can be adopted for prevention and control.
5.1 Agricultural control
The first is to remove weeds in the field, at the edge of the ground and at the edge of the canal in time to reduce the overwintering host plants of the double-spotted fluorescent leaf beetle; the second is to timely replenish the farmland after the double-spotted fluorescent leaf beetle is serious and the prevention and control is to promote the vegetative growth and reproductive growth of crops.
5.2 Biological control
Protect and use predators (e.g., ladybugs, spiders, etc.).
5.3 Chemical control
Due to the complexity of the overwintering site of the insect, therefore, in the control strategy should follow the principle of "first treat outside the field, then in the field", the control of adult insects should be controlled on the field edge, the head, the canal edge and other host plants just feathered out of the adult insects; pharmaceutical control should be before the adult insects bloom, can use permethrin agents, such as 2.5% high-efficiency cypermethrin emulsion 1 500 times liquid, or 50% octylthion emulsion 1 500 times liquid spray, the agent should focus on spraying around the female spike, spraying time should avoid the corn flowering period, so as not to affect pollination Because pests have the ability to fly, it is necessary to increase unified prevention and control according to the region, so as to achieve better control results.
China Agricultural Technology Extension Network